Many devices, such as mobile telephones, personal computers (PCs), handheld computers, and personal digital assistants (PDAs), enable users of such devices to send and receive communication messages using a variety of electronic communication methods. For example, communication messages may be sent and received using email, instant messaging (IM), text messaging (also called short messaging service or SMS), and voice over internet protocol (VOIP).
Having the ability to communicate using these communication methods is very useful and efficient. However, the usefulness and efficiency of such communication methods is often reduced because of unwanted and undesirable messages. (Such messages may be termed “spam.” While the term “spam” is typically used to refer to unwanted and undesirable email messages, the term “spam” will be used herein to refer to unwanted and undesirable messages sent via any communication method.) Users may receive a large amount of spam. Users may spend a large amount of time sorting through received messages and deleting unwanted messages. Additionally, some communication messages may contain content that is inappropriate for young users.
Users may wish to prevent spam from being delivered to the user. Alternatively, users may wish to segregate messages that may be spam into a separate category or folder to facilitate deletion of messages that are spam. Some methods exist which attempt to prevent spam from reaching the user. One method is to search each incoming communication message for a predefined list of words or phrases that may be indicative of spam. This method may be termed the “keyword method.” If a word or phrase from the predefined list is found in the communication message, the communication message may not be delivered to the user. The keyword method may not prevent all spam, however, because senders of spam may be able to circumvent such a method. One way to circumvent the keyword method is to avoid using any words or phrases from the predefined list in the message. Senders of spam may, for example, deliberately misspell a word in the message that is on the predefined list. Such a misspelling may cause the keyword method to fail and allow the message to be delivered to the user.
Another method of preventing spam is to compare the communication identifier (e.g., email address, IM screen name, telephone number) of the sender to a predefined list of authorized senders. Such a list may be termed a “white list,” and the method may be termed the “white list method.” If the sender's communication identifier is not on the predefined white list, then the communication message may not be delivered to the user. One drawback of the white list method, however, is that the list of authorized users must be frequently updated to ensure that desired messages are delivered. Additionally, the white lists consume memory storage space, typically either in the user's communication device or in a network device, such as an email server.